ST. LOUIS — In spite of St. Louis County Prosecutor Robert McCulloch's promises to make all witness testimony in the Michael Brown shooting case public so he could show the process was fair and impartial, McCulloch's office now acknowledges that it kept some records secret at the behest of federal authorities who are still investigating the incident.

The acknowledgment came after a review by KSDK-TV found several key documents were missing from the thousands of pages released by McCulloch's office on Nov. 24, shortly after the prosecutor announced that the grand jury had decided not to indict Ferguson police officer Darren Wilson for killing the unarmed teen.

McCulloch's executive assistant, Ed Magee, said the office released everything it still had when the case was closed, but had "turned over and relinquished control" of some FBI's interviews conducted in connection with the shooting.

Dorian Johnson interview withheld

A team of investigative reporters from around the country reviewed the transcripts released by McCulloch's office, which included law enforcement interviews with 24 witnesses. Most conspicuous in its absence was the joint federal-county interview with the witness who had been closest to the deadly confrontation, Michael Brown's friend Dorian Johnson.

Transcripts of the grand jury proceedings indicate that interview was conducted on Aug. 13, four days after the shooting, and lasted more than two hours. Transcripts of that interview were provided to grand jurors, who then listened to a recording of it in its entirety, the records show.

But, while McCulloch's office provided the public with recordings of six different television interviews Johnson conducted with local and national media, there is no record of what Johnson told law enforcement before his grand jury testimony. Neither the audio recording nor the transcript of Johnson's FBI interview was included in the materials released.

McCulloch repeatedly said that following witness testimony over time, to see if they changed their stories, was a critical part of measuring a witness' veracity. During his press conference Nov. 24, he listed several specific times when witnesses whose stories suggested Wilson had not been justified in using deadly force, altered their testimony after being challenged or after learning the results of autopsies.

McCulloch encouraged the media and the public to review the records he released with that in mind.

"We presented to this grand jury … all the evidence there could possibly be, all of which will be available … so everyone will be able to examine that same evidence and come to their own conclusion," McCulloch said during the announcement of the grand jury's decision.

Protesters use chalk to outline pastor Charles Burton during a demonstration at the Ferguson, Mo., police station on Oct. 13. Activists have planned a day of civil disobedience to protest the shooting of Michael Brown and Vonderitt Meyers Jr. Charles Rex Arbogast, AP

Demonstrators stage a protest in St. Louis. Demonstrators were protesting the Aug. 9 shootings of Michael Brown by a police officer in suburban Ferguson, and Vonderrit Myers Jr., who was killed by a St. Louis police officer on Oct. 8. Scott Olson, Getty Images

Demonstrators march through the streets Oct. 13 in St. Louis. The area has struggled to heal since riots erupted after the killing Aug. 9 of Michael Brown, 18, by a police officer in suburban Ferguson. Another teenager, Vonderrit Myers, was killed by a St. Louis police officer Oct. 8. Scott Olson, Getty Images

Protesters march past the St. Louis Arch in St. Louis, Mo., on Oct. 11. More than 1,000 gathered Saturday in downtown St. Louis for a second day of organized rallies to protest Michael Brown's death and other fatal police shootings in the area and elsewhere. Charles Rex Arbogast, AP

Ferguson has been plagued with protests which have since the death of 18-year-old Michael Brown, who was shot and killed by Darren Wilson, a Ferguson police officer, on Aug. 9. Scott Olson, Getty Images

But Marcia McCormick, a professor at Saint Louis University Law School specializing in civil rights law, said, "We don't have the full picture."

"To the extent that Dorian Johnson is one of the primary witnesses suggesting that Officer Wilson might not have been justified in shooting Mr. Brown, then knowing what Mr. Johnson said earlier might help us know if he was one of the people who gave consistent statements or inconsistent statements," McCormick said. "It would help us understand a credibility determination that might have been made."

Other witness statements missing?

It appears that Johnson's statement to the FBI isn't the only witness statement missing from the public record.

McCulloch's office labeled the witness interview transcripts it released by witness number, up to Witness #64. But only 24 different witnesses' interviews with law enforcement were included in the information released.

Asked about that, Magee said the federal government specifically asked the county not to release records that are part of the FBI's ongoing Civil Rights probe.

"Those are not our records," he said.

And yet, KSDK-TV's investigative team found that more than half of the witness interviews that were made public were conducted by FBI agents or federal prosecutors. Three were joint county-federal interviews — just as Johnson's was — and 10 of the 24 witnesses were interviewed exclusively by federal agents, with no county officials present.

McCulloch said last month that all of the evidence and testimony gathered by county detectives was shared with federal authorities and vice-versa, but Magee said, "Whatever we released is not what the FBI had."

The Department of Justice declined to comment about what it instructed the county prosecutor to withhold from public release and why.

McCormick, the SLU professor, said it's possible that the federal authorities allowed certain FBI interviews to be released because they may have not been important to the Justice Department's civil rights investigation.

"The question that the federal government is investigating, the Department of Justice is looking at, is a different legal question," she said. "It's not a question of whether Officer Wilson was justified under Missouri law in the actions that he took, but whether when he acted, he recklessly disregarded the civil rights of Mr. Brown."

KSDK-TV has filed a formal Freedom of Information Act request, asking for the federal government's full investigative file in the case as soon as its case is closed.

There is one other way the missing witness statements could become available, McCormick said: If Brown's family requests them as a part of a civil lawsuit against Wilson or the Ferguson Police Department and subsequently shares them with the public.